Emission of CO2 enhanced by thiamethoxam and cadmium in agricultural soil.

The coexistence of neonicotinoid insecticide thiamethoxam (TMX) and heavy metal cadmium (Cd) is quite common in agricultural soils, yet their effects on the emission of greenhouse gas CO2 remain insufficiently studied. To address this issue, microcosms spiked with singe or combined TMX (20 mg/kg) and Cd (20 mg/kg) in soil were studied for 90 days. It turned out that single TMX (+12.13 %) and Cd (+22.76 %) both stimulated the emission of CO2, and the combined TMX and Cd exhibited synergic effect (+51.00 %). The presence of Cd reduced the attenuation of TMX (-3.32 %), while the presence of TMX increased the attenuation of Cd (+3.11 %). The relative abundances of bacteria Sphingomonas, Devosia, Erythrobacter, Phaselicystis, Woeseia, FFCH7168, Rhizorhapis, Hamadaea and genes related to sugar metabolism, glycolysis and the TCA cycle were found positively correlated to CO2 emission in the studied microcosms (p < 0.05). Results from this study provide scientific basis for developing sound environmental policies that aim to reduce CO2 emission from agricultural soils.